Field of the Invention
The invention relates to a device substrate and a fabricating method thereof, and more particularly relates to a device substrate having exposure openings and a fabricating method thereof.
Description of Related Art
As information technology, wireless mobile communication, and information appliances rapidly develop in the recent years, the input devices for a great many information products have been changed from the conventional keyboards or mice to touch display panels for the purposes of convenience, miniaturization, and being user-friendly. Especially, the touch display panel has become the most popular product among all.
The conventional touch display panel is mainly composed of an active device array substrate, an opposite substrate (e.g. color filter substrate), and a display medium disposed between these substrates. Moreover, multiple main spacers and multiple secondary spacers are located between the active device array substrate and the opposite substrate and may be disposed on the opposite substrate or the active device array substrate, for example. In the fabricating method of the device substrate (e.g. opposite substrate, color filter substrate, or active device array substrate, etc.) for the conventional touch display panel, a phase shift mask, half tone mask, or gray tone mask is required for fabricating the main spacers and the secondary spacers that have different heights. The spacers are generally formed of a transparent material and have high UV transmittance. Therefore, the exposure amount needs to be very low in order to achieve a high level difference (i.e. large height difference). However, the control capability of the level difference is limited to the stability of the phase shift mask, half tone mask, or gray tone mask at low penetration. Besides, because the transmittance of the phase shift mask, half tone mask, or gray tone mask is a fixed value after the mask is completed at the factory, the adjustable range of the exposure amount is also limited. In addition, the phase shift mask, half tone mask, or gray tone mask further faces problems such as high production costs and longer stock preparation time, etc. Hence, how to use a general mask (that is, without using the phase shift mask, half tone mask, or gray tone mask) to fabricate main spacers and secondary spacers with different heights while maintaining favorable level difference (i.e. height difference) control capability is an issue that needs to be overcome in the production technology of display panels.